Novel acetal

ABSTRACT

Synthesis of, and intermediates for, trans-4, cis-7 tridecadienyl acetate, attractant for the male potato tuberworm moth.

This is a division of application Ser. No. 602,153, filed Aug. 6, 1975.

This invention relates to the synthesis of, and intermediates for, thecompound trans-4, cis-7 tridecadienyl acetate which is an attractant forthe male potato tuberworm moth.

The potato tuberworm moth, Phthorimaea operculella is a pest of potatoesin many areas of the world. The synthesis of the male attractant,tridecadienyl acetate, with the isomeric requirement trans(E) at C-4 andcis(Z) at C-7 is of considerable utility. The synthetic compound isuseful for monitoring the insect population and thereby determine theneed for applying insecticide.

The synthesis of the present invention can be outlined as follows:##STR1##

In the practice of the above outlined synthesis, the acetal I isprepared by the reaction of ethyl vinyl ether and 4-pentyn-1-ol in thepresence of p-toluenesulfonic acid. CF. Eaton et al, J. Org. Chem. 37,1947 (1972). The acetal I is then treated with n-butyllithium to preparethe lithium salt thereof which is reacted with paraformaldehyde toobtain the acetylenic alcohol II. Stereoselective reduction of theacetylenic alcohol II with lithium aluminum hydride in tetrahydrofuranunder reflux gives the trans allylic alcohol III. The alcohol III isthen converted to the allylic chloride IV using methanesulfonylchloride, lithium chloride, and 2,4,6-trimethylpyridine without anydetectable rearrangement or loss of stereochemistry and without attackon the acid-sensitive acetal protecting group. CF. Collington et al, J.Org. Chem. 36, 3044 (1971). The allylic chloride IV is then reacted with1-heptynyl-1-magnesium bromide by heating in tetrahydrofuran underreflux in the presence of a catalytic quantity of cuprous chloride toyield the 4E-ene-7-yne acetal V. Hydrolysis of the acetal VI withtrichloroacetic acid gives the alcohol VI which is crystallized frompentane at -74° and then distilled to give pure 4E-ene-7-yne alcohol VI.Careful partial hydrogenation of the alcohol VI at 0° over Lindlarcatalyst in hexane containing synthetic quinoline gives 4E,7Z-dienylalcohol VII which is acetylated to yield 4E,7Z-tridecadien-1-yl acetateVIII (98% purity by glc analysis).

The attractant VIII is used in conjunction with an insect trap which isprovided with a sticky surface to hold the adult moth. A charge of about100 to 500 micrograms of VIII in a suitable inert holder such as a smallpolyethylene cap or a rubber septa is a sufficient amount to lure theadult male moth to the trap. The cap or septa is held in place by thesticky surface of the cap. The attractant can also be mixed with a resinor wax and extruded or molded at low temperature to produce largequantities of the attractant in convenient form for use. A suitablepolymeric carrier is described by McKibben et al., U.S. Pat. No.3,803,303.

The following examples are provided to illustrate the practice of thepresent invention. Temperature is given in degrees Centigrade.

EXAMPLE 1

To 72 g (1 mol) of ethyl vinyl ether was added 70 mg (0.37 mmol) ofp-toluenesulfonic acid monohydrate and the solution was cooled to 0°.4-Pentyn-1-ol (44 g; 0.52 mol) was then added at ≦20° and the reactionwas stirred at ≦20° for 1 hr. The reaction was then cooled to 0° and 5ml of saturated aqueous K₂ CO₃ was added. After 15 min., solid K₂ CO₃was added to remove the water and the solution was filtered and theexcess ethyl vinyl ether was removed from the filtrate at atmosphericpressure. The residue was distilled in vacuo to give 66.79 g (82% yield)of the acetal I, bp 70°-72° (20 mm) nmr (CCl₄) δ 1.16 (t, 3, J = 7 Hz,OCH₂ CH₃), 1.23 [d, 3, J = 5.5 Hz, OCH(CH.sub. 3)O], 1.76 (m, 3, OCH₂CH₃ and C.tbd.CH), 2.28 (m, 2, CH₂ C.tbd.CH), and 4.62 ppm [q, 1, J =5.5 Hz, OCH (CH₃)O].

EXAMPLE 2

To 70 ml of ether cooled to -10° was added 64.6 ml (0.10 mol) of 1.55 Mn-butyl-lithium in hexane and then 15.6 g (0.10 mol) of the acetal I wasadded while maintaining the temperature at ≦-10°. The solution was thenstirred for 10 min and then 30 ml of tetrahydrofuran was added at -10° .The solution was warmed to 0° and 3.60 g (0.12 mol) of paraformaldehydewas added in one portion. The reaction was allowed to warm to roomtemperature over 45 min and then was heated under reflux for 3 hr. Thesolution was then cooled to room temperature and poured into ice waterand the mixture was extracted with ether:pentane (1:1). The organiclayer was washed with saturated aqueous NH₄ and was dried (MgSO₄).Removal of the solvent in vacuo followed by distillation of the residuegave 13.24 g (71% yield) of the acetylenic alcohol II, bp 91° (0.20 mm)nmr (CCl₄) δ 1.17 (t, 3, J = 7 Hz, OCH₂ CH₃), 1.23 [d, 3, J = 5.5 Hz,OCH(CH₃)O], 3.05 (t, 1, J = 5.5 Hz, OH), 4.10 (m, 2, CH₂ OH), and 4.62ppm [q, 1, J = 5.5 Hz, OCH(CH₃)O].

Anal. Calcd for C₁₀ H₁₈ O₃. C, 64.49; H, 9.74. Found: C, 64.29; H, 9.73.

EXAMPLE 3

To 12.24 g (65.7 mmol) of the acetylenic alcohol II in 120 ml oftetrahydrofuran was added 15.8 ml (68 mmol) of 4.3 M lithium aluminumhydride in ether and the reaction mixture was heated under reflux for1.5 hr. The solution was then cooled, and ice was added to destroy theexcess reagent and the reaction mixture was poured into saturatedaqueous NH₄ Cl. The mixture was extracted with ether:hexane (1:1) andthe organic layers were combined and washed with saturated aqueous NH₄Cl, brine and were dried (MgSO₄). Removal of the solvent anddistillation of the residue gave 10.44 g (84.4% yield) of the alcoholIII, (98% pure by glc analysis), bp 102°-104° (0.40 mm) nmr (CCl₄) δ1.17 (t, 3, J = 7 Hz, OCH₂ CH₃), 1.23 [d, 3, J = 5.5 Hz, OCH(CH₃)O],3.97 (br s, 2, CH₂ OH), 4.62 [q, 1, J = 5.5 Hz, OCH(CH₃)O], and 5.62 ppm(m, 2, CH=CH).

Anal. Calcd for C₁₀ H₂₀ O₃ : C, 63.80; H, 10.71. Found: C, 63.82; H,10.60.

EXAMPLE 4

To 13.8 g (0.114 mol) of 2,4,6-trimethylpyridine and 19.58 g (0.104 mol)of the alcohol III was added 4.41 g (0.104 mol) of lithium chloridedissolved in 80 ml of dimethylformamide. The mixture was cooled to 0°and 13 g (0.114 mol) of methanesulfonyl chloride was added. The yellowsolution was stirred for 3.5 hr at 3° and then was poured into ice-waterand the mixture was extracted with pentane. The pentane layer was washedwith aqueous CuSO₄, brine, and was dried (Na₂ SO₄) and the solvent wasremoved to give 20 g (93% yield) of the allylic chloride IV: nmr (CCl₄)δ 1.14 (t, 3, J = 7 Hz, OCH₂ CH₃), 1.21 [d, 3, J = 5.5 Hz, OCH(CH₃)O],3.96 (d, 2, J = 6 Hz, CH₂ Cl), 4.57 [q, 1, J = 5.5 Hz, OCH(CH₃)O], and5.67 ppm (m, 2, CH=CH).

EXAMPLE 5

To a solution of 1-heptynyl-1-magnesium bromide (prepared from 120 mmolof 1 -heptyne and 120 mmol of EtMgBr in 120 ml of tetrahydrofuran,heated under reflux for 2 hr) was added 1.60 g (16 mmol) of cuprouschloride and the mixture stirred at room temperature for 20 min. Then 20g (0.097 mol) of the allylic chloride IV in 30 ml of tetrahydrofuran wasadded and the reaction mixture was stirred to 60° for 4.5 hr. After themixture had been cooled, aqueous NH₄ Cl was added and the mixture wasextracted with pentane. The pentane layer was washed with saturatedaqueous NH₄ Cl, brine, and dried (MgSO₄) and the solvent was removed togive 25.12 g (97% yield) of crude acetal V, bp 103°-104° (0.12 mm) nmr(CCl₄) δ 1.13 (t, 3, J = 7 Hz, OCH₂ CH₃), 1.21 [d, 3, J = 5.5 Hz,OCH(CH₃)O], 2.75 (br s, 2, C.tbd.CCH₂ CH=CH), 4.54 [q, 1, J = 5.5 Hz,OCH(CH₃)O], and 5.47 ppm (m, 2, CH=CH).

EXAMPLE 6

To a solution of 25.12 g (94.3 mmol) of the acetal V in 250 ml oftetrahydrofuran was added 50 ml of water and 0.5 g (3.06 mmol) oftrichloroacetic acid and the mixture was stirred at room temperature for17 hr, and then was heated under reflux for 5 hr. To the cooled solutionwas added 25 ml of 2 M aqueous Na₂ CO₃ and the mixture was extractedwith ether. The organic layer was washed with saturated aqueous NaCl andwas dried (MgSO₄), and the solvent was removed and the residue wasdistilled to give 12.63 g (69% yield) of the alcohol VI. The distilledmaterial was crystallized by dissolving it in 120 ml of pentane andcooling the solution to -74° and collecting the crystals at -74° toyield 11.04 g (60% yield) of VI (98.8% pure by glc analysis): bp 95°(0.10 mm) nmr (CCl4) δ 2.78 (br s, 1, C.tbd.CCH₂ CH=CH), 3.58 (t, 2, J =6 Hz, CH₂ OH), and 5.52 ppm (m, 2, HC=CH).

Anal. Calcd for C₁₃ H₂₂ O: C, 80.35, H, 11.41. Found: C, 80.19; H,11.43.

EXAMPLE 7

A solution of 11.04 g (57 mmol) of the alcohol VI in 40 mltetrahydrofuran was added to a prehydrogenated suspension of 1.36 g ofLindlar Catalyst (from Engelhard Industries) in 150 ml of hexanecontaining 0.33 ml of synthetic quinoline at 0°. The acetylene washydrogenated at 2°-4° (the reaction was followed by glc). When thereaction was complete (by glc analysis) celite was added and the mixturewas filtered, and the solvent was removed from the filtrate.Distillation of the residue gave 9.53 g (85% yield) of the diene VII: bp83°-85° (0.09 mm) nmr (CCl₄) δ 2.70 (br s, CH=CHCH₂ CH=CH), 3.55 (t, 2,J = 6 Hz, CH₂ OH), and 5.40 ppm (m, 4, CH=CHCH₂ CH=CH).

Anal. Calcd for C₁₃ H₂₄ O: C, 79.53; H, 12.32. Found: C, 79.56; H,12.25.

EXAMPLE 8

To a solution of 9.13 g (46.5 mmol) of the diene VII in 9.37 ml (0.116mol) of pyridine was added 5.50 ml (58.3 mmol) of acetic anhydride. Thesolution was stirred 23 hr at room temperature, then was cooled to 0°,and ice was added, and the solution was poured into ice and water andthe mixture was extracted with pentane. The pentane layer was washedwith ice cold aqueous 10% HCl, and 5% aqueous NaHCO₃, brine and wasdried (Na₂ SO₄). The solution was filtered through a column of 80 g offlorisil (Act. III), using pentane as eluent. Removal of the pentanefrom the eluate followed by distillation of the residue gave 8.30 g(74.9% yield) of VIII (97.7% pure by glc analysis at 180° on a 4 m × 2mm (i.d.) glass column packed with 10% OV-17 on 100/120 mesh ChromosorbW-AW-DMCS), bp 75°-80° (0.03 mm) nmr (CCl₄) δ 1.99 (s, 3, COCH₃), 2.71(br s, 2, CH=CHCH₂ CH=CH), 3.99 (t, 2, J = 6 Hz, CH₂ OAc), and 5.38 ppm(m, 4, CH=CHCH₂ CH=CH); mass spectrum (20 ev) m/e (rel intensity) M⁺ 238(˜0), 178 (22), 150 (14), 135 (16), 121 (33), 107 (38), 93 (74), and 79(100).

Anal. Calcd for C₁₅ H₂₆ O₂ : C, 75.58; H, 11.00. Found: C, 75.75; H,10.89.

Nmr spectra were determined on a Varian T-60 spectrometer. Gas-liquidchromatographic analysis (glc) were performed on Model 402Hewlett-Packard instruments equipped with hydrogen flame ionizationdetectors.

What is claimed is:
 1. The trans compound of the formula: ##STR2##